Cardiogenic shock: thrombolysis or angioplasty?

Cardiogenic shock (CGS) occurs in 3 to 20% of patients presenting with acute myocardial infarction (MI), and it generally involves dysfunction of at least 40% of the total myocardial mass. Prior to the advent of balloon angioplasty and thrombolysis, in-hospital mortality was greater than 75%. This mortality rate has been consistent in reported series despite the advent of cardiac intensive care units, vasopressor, inotropic, and vasodilator therapy. Intra-aortic balloon counterpulsation therapy provides hemodynamic improvement, and it may provide some mortality benefit when used in conjunction with appropriate revascularization. Survival studies have shown that patency of the infarct-related artery is a strong predictor of survival. No randomized trials have been completed to examine which reperfusion therapy best treats this emergent situation. Subgroup analysis of large scale, multicenter trials, although underpowered, has shown no improvement in mortality with use of thrombolytic agents, leading many to advise use of mechanical intervention. In patients who present with acute MI with contraindications to thrombolysis, primary angioplasty is the treatment of choice. At selected centers, primary angioplasty is comparable to or better than thrombolytic therapy for patients presenting with acute MI, with or without CGS. Studies examining angioplasty in patients with CGS have shown high procedural success rates (75%) and reduced in-hospital mortality (44%), particularly in those patients with successful revascularization. Emergency bypass surgery may improve survival, but it is costly, unavailable to many, and often leads to excessive delays in therapy. If available, we believe that primary angioplasty is the treatment of choice for patients with CGS.     

Detecting failed thrombolysis in the accident and emergency department

The primary objective in managing a patient with ST segment elevation myocardial infarction (STEMI) is to establish reperfusion in the infarct-related artery and to maintain it. Two approaches to coronary reperfusion are used in the UK - primary angioplasty and intravenous thrombolysis. Primary angioplasty is the gold standard approach to managing STEMI, but in the UK (due to financial, resource and personnel limitations) this is not the first-line treatment. Thrombolytic therapy remains the most widely used approach and the benefits of such an approach are irrefutable; thrombolysis saves lives, reduces infarct size and limits left ventricular dysfunction. However, data from the thrombolytic trials also suggest that 30-40% of patients fail to reperfuse with standard thrombolytic therapy. Similar data demonstrates that patients who do not sustain adequate perfusion in the infarct-related artery have a poor prognosis and increased mortality rates. As long as thrombolysis remains the standard therapy for STEMI, it is important that patients in whom the treatment has been unsuccessful are swiftly recognised and appropriate interventions instituted. The criteria to assess successful reperfusion of the infarct-related artery need to be simple to apply, easy to interpret and non-invasive. This article will discuss the most useful criteria to make such a diagnosis and suggest approaches to enable recognition of 'failed thrombolysis' in the accident and emergency department. The current views on managing failed thrombolysis will conclude the article.     

Thrombolytics.

Thrombolytic therapy is the most recent advance in the treatment of acute myocardial infarction. Several research trials have been conducted worldwide in the last decade that have established that thrombolytic therapy has reduced mortality 50%, reduces the size of the infarction, improves left ventricular function, and reduces the incidence and severity of congestive heart failure. The three most commonly used thrombolytic agents at this time are streptokinase, tissue plasminogen activator, and anisoylated plasminogen-streptokinase activator complex. All three agents can be administered through a peripheral intravenous. Recent research results have reported similar efficacy on 5-week mortality of all three agents. Careful assessment of prospective patients is essential since bleeding complications are the most serious side effect of this therapy. Nursing care of a patient undergoing thrombolytic therapy includes careful assessment of the patient for contraindications in the patient's medical history, assessment of potential allergic and bleeding complications, and evaluation of the reperfusion markers. Patients are subsequently treated with anticoagulants, aspirin, or dipyridamole. It appears that thrombolytic therapy will become increasingly available to all patients with a diagnosis of suspected acute myocardial infarction. At present, treatment with thrombolytic agents is less available in the United States compared to Europe.     

急诊经皮冠状动脉腔内成形术与溶栓治疗急性心肌梗死的疗效比较

目的比较急诊经皮冠状动脉腔内成形术(PTCA)与溶栓治疗急性心肌梗死(AMI)的临床疗效.方法46例AMI患者,21例行急诊PTCA治疗,25例行溶栓治疗.结果急诊PTCA组梗死相关血管(IRA)成功开通的有20例,成功率为95%;溶栓组IRA再通有17例,成功率为68%,两组比较,P<0.01.出院前左心室射血分数(LVEF)急诊PTCA组为0.53±0.10,溶栓组为0.54±0.16,病死率分别为5%和4%,两组间差异无显著性(P>0.05).急诊PTCA组的平均费用明显比溶栓组高(P<0.05).结论急诊PTCA与溶栓治疗AMI患者,可使IRA充分有效地开通,故在条件允许的医院,可优先考虑行急诊PTCA治疗AMI.     

Reperfusion in acute myocardial infarction

During the past decade, the general acceptance of the primary role of thrombosis in acute myocardial infarction (AMI) has led to intense interest in the potential efficacy of reperfusion therapy, particularly thrombolytic therapy, in AMI. Accumulating evidence indicates that systemic thrombolytic therapy administered early after the onset of symptoms of AMI can restore infarct-related artery patency, salvage myocardium, and reduce mortality. Recommendations about the proper use of thrombolytic therapy, contraindications, and concomitant therapies (such as aspirin, heparin, nitrates, beta-adrenergic blocking agents, and calcium channel blockers) are reviewed. Although percutaneous transluminal coronary angioplasty (PTCA) is useful for subsets of patients with AMI (for example, patients with anterior infarctions with persistent occlusion of the infarct-related artery after thrombolytic therapy and those with cardiogenic shock), a conservative strategy, including angiography and PTCA only for postinfarction ischemia, is indicated for most patients with AMI in whom initial thrombolytic therapy is apparently successful. The use of PTCA after failed thrombolysis or as direct therapy for AMI seems promising, although further comparisons of PTCA and intravenous thrombolytic therapy are needed. Ongoing studies should help further define the risk-to-benefit ratio of various reperfusion strategies in different subsets of patients, define time limitations for reperfusion therapy, and provide data on therapeutic modalities that will limit reperfusion injury and therefore enhance salvage of myocardium.     

溶栓技术在ST段抬高型心肌梗死救治中的地位

急性ST段抬高型心肌梗死的再灌注治疗中, 溶栓治疗作为解决这一血栓性疾病的治疗方式, 仍应具有相当重要的地位。近些年溶栓治疗用于心肌梗死治疗的相关临床研究已分别证实:(1)在发病时间较早且介入开始时间可能延误较长(>2 h)的情况下考虑首选; (2)在拟采取介入治疗但因有一些延误时(1 h)考虑使用低剂量溶栓药物辅助溶栓后再行介入治疗; (3)在冠状动脉内血栓负荷严重时冠状动脉内使用溶栓药物再行介入治疗, 以上3种情况临床应用时应予以充分考虑。     

Acute MI in the elderly: choosing the best revascularization method. Risks and benefits of thrombolysis, angioplasty, and bypass surgery

MI is often recognized less promptly in elderly patients than in younger patients; thus, the best opportunity for reperfusion is often missed. If infarction is diagnosed in less than 12 hours and there are no strong contraindications, thrombolytic therapy is appropriate for the elderly. Coronary angioplasty is a suitable alternative if performed promptly, especially because elderly patients are more likely to have contraindications to, or higher mortality from, thrombolysis. Predictors of unfavorable outcome following angioplasty for acute MI in the elderly include multivessel disease, occlusion of the infarcted artery, and cardiogenic shock. CABG surgery (performed during infarction or in the peri-infarct setting) is also an option for those elderly patients who are hemodynamically stable.     

The role of angioplasty in acute myocardial infarction

The role of percutaneous transluminal coronary angioplasty (PTCA) in the management of acute myocardial infarction (AMI) has not yet been precisely defined. The longest experience with PTCA in this setting has been in patients who are not candidates for thrombolytic therapy and in patients in whom thrombolysis has failed. Clinical interest has recently focused on direct use of PTCA (instead of thrombolysis) as the initial approach to reperfusion in AMI. We review the conceptual bases for both thrombolytic therapy and PTCA in AMI, and we then detail the clinical experience with PTCA in a variety of patient populations with AMI to guide use of both therapies in this setting.     

Coronary Thrombolysis

Randomized trials have demonstrated the overall benefits and risks of thrombolytic therapy for acute myocardial infarction, and have evaluated adjunctive drug therapies, adjunctive and primary angioplasty, various approaches to the timing of thrombolysis, and post-thrombolysis management. Three questions, which remain unanswered, are addressed in this Point-Counterpoint Series. The GUSTO trial provides convincing evidence of the greater efficacy of rt-PA by comparison to SK, but the size of the benefit is uncertain, as are the risk benefit ratios and cost-effectiveness in various patient subgroups. The issues of whether or not routine angiography is appropriate for patients who have received coronary thrombolysis remains unresolved. For the present, clinical guidelines are likely to advise against routine angiography, while many cardiologists, concerned about the shortcomings of available studies, may wish to undertake coronary angiography in many of their patients, even though definitive proof of its benefit is lacking. Although randomized clinical trials suggest a benefit of primary angioplasty over thrombolytic therapy, further studies are required to clarify the comparative benefits in terms of clinically important outcomes and cost-effectiveness.     

Heal thyself: Potential applicability of stem cell therapy in the management of heart disease

Acute myocardial infarction results in regional necrotic heart tissue that is considered irreversible. Although angioplasty and thrombolytic therapy can remove the offending atherosclerotic plaque and thrombi, both therapies are dependent upon timely recognition and initiation of treatment and thus have a limited window of opportunity. No currently available therapy has the capability to restore cardiomyocytes or to replace myocardial scar tissue with contractile tissue. In animal models, use of a wide range of cells such as fetal cardiomyocytes, skeletal myoblasts, and bone marrow stem cells have been shown to differentiate into functional cardiomyocytes. In addition, transplantation of adult stem cells directly into the area of infarction has shown clinical promise. This article explores the current data on extramedullary hematopoiesis, stem cell differentiation, and stem cell therapy and its ability to repair injured or ischemic cardiac tissue.     

The contemporary management of acute myocardial infarction.

The contemporary management of acute myocardial infarction continues to evolve rapidly. The ultimate goal of therapy is timely, complete, and sustained myocardial reperfusion. There is a powerful time-dependent effect on mortality, and thus the balance between the time and likelihood of maximal reperfusion is crucial in deciding whether to use primary percutaneous balloon angioplasty or thrombolysis as the initial reperfusion strategy. Newer thrombolytic agents allow for equivalent coronary reperfusion compared with the standard accelerated alteplase (tPA) regimen with the advantage of easier dosing regimens. Low molecular weight heparin has been shown to be superior to unfractionated heparin and likely will be the standard of care in the near future. The use of glycoprotein IIb/IIIa inhibitors has been shown to decrease the short- and long-term complication rates in patients with acute coronary syndromes treated medically and with percutaneous coronary interventions; however, the choice of the optimal agent and dosing regimen in various clinical settings remains controversial. Combination therapy with low-dose fibrinolytics, glycoprotein IIb/IIIa inhibitors, and low molecular weight heparin, with or without subsequent early planned percutaneous coronary interventions, may provide the optimal strategy for maximal coronary reperfusion, but the results of large, randomized mortality trials currently underway need to be analyzed. Risk stratification will continue to play a major role in determining which patients should receive a specific therapy. The care of the patient with an acute myocardial infarction will continue to be a challenge requiring the proper selection from the vast pharmaceutic and interventional options available.     

Results of treatment of patients with acute myocardial infarction and high risk of cardiac complications

The authors compare the results of the treatment of 883 patients with acute myocardial infarction (AMI) referred to the group with high risk of cardiac complications based on the TIMI, GRACE, and TIMI Il assessment stratification scales. 487 patients were treated by conservative therapy using anticoagulative (n = 414) or thrombolytic (n = 73)) agents. 396 underwent surgical treatment (coronary artery bypass surgery (101) or percutaneous coronary angioplasty (295)). The mortality rate in the group treated by percutaneous coronary angioplasty was 13.6 (p < 0.001), 7.2 (p < < 0.01) and 3.5 (p < 0.05) times lower than after anticoagulation therapy, thrombolysis and coronary bypass surgery respectively. It is concluded that percutaneous coronary angioplasty has advantages over other modalities for the treatment of patients with acute myocardial infarction and high risk of cardiac complications.     

Thrombolytic therapy versus primary angioplasty in the treatment of acute myocardial infarction

The quest to identify the acute interventional approach that will achieve the lowest mortality rate with the fewest adverse events has led to a continued controversy surrounding the relative merits of thrombolytic therapy compared with primary angioplasty in the setting of acute myocardial infarction. This article summarizes the benefits and limitations of each reperfusion strategy and highlights adjunctive therapies that will enhance either treatment strategy.     

Current trends in the treatment and outcome of acute myocardial infarction (MI)

Current trends in the treatment and outcome of acute myocardial infarction were studied in a trial entering 2411 patients with macrofocal myocardial infarction (MI) treated in 1993-1998. There were many cases of severe and repeated MI. The age of the patients tends to increase. Lethal outcomes' probability is very high in multiple stenosis of the coronary arteries. This condition is associated with a high risk of cardiac insufficiency progression because of inadequate blood supply to necrosis-free myocardial zones. Thrombolytic therapy (TLT), ACE inhibitors reduce lethality but their use is limited by such factors as concurrent diseases, time from MI onset, rethrombosis risk. As a result, only 1/5 of the patients received pharmacological treatment. Balloon angioplasty is indicated in contraindications to TLT, in TLT failure or large residual stenosis. ACE inhibitors slow down the progression of cardiac insufficiency giving time for surgical revascularization. Updated treatment of MI improved its outcomes, but further progress in lowering MI lethality will be insignificant unless efficient methods providing adequate blood supply to the myocardium are introduced.     

早期再灌注对急性心肌梗死伴室壁瘤形成的阻抑效应和心功能改善作用的超声心动图观察

目的　超声心动图观察早期再灌注对急性心肌梗死伴室壁瘤形成的阻抑效应和心脏收缩功能改善作用。方法　发病 12h以内急性前壁心肌梗死伴室壁瘤形成患者 98例,随机分为经皮腔内冠状动脉成形术(PCI)组(36例)、溶栓组(31)例和常规药物治疗组(31例),三组患者均在治疗后 2周、12周、24周分别行超声心动图测量左室收缩末期容积(LVESV)、左室舒张末期容积 (LVEDV),并以体表面积校正为左室收缩末期容积指数(LVESVI)、左室舒张末期容积指数(LVEDVI),同时测左室射血分数 (LVEF)、局部室壁运动指数 (RWMI)、左室质量(LVM),后者与体表面积相除得到左室质量指数(LVMI),评价LVESVI、LVEDVI和心室收缩功能改善状况。结果　治疗后 2周,PCI组和溶栓组各参数优于药物治疗组,治疗后 12周,PCI组LVESVI、LVEDVI低于溶栓组(均P<0. 05),溶栓组各参数优于药物治疗组(均P<0. 05)。PCI组和溶栓组各参数自身前后比较明显改善(均P<0. 05),LVEF较 2周时显著增高(P<0. 05)。治疗后 24周,PCI组LVEDVI、LVESVI仍低于溶栓组(P<0. 05),PCI组和溶栓组各参数均优于药物治疗组 (均P<0. 05),PCI组LVESVI、LVEDVI、RWMI较 2周、12周均减小(均P<0. 05),LVEF较 2周、12周显著增高(均P<0. 05);溶栓组各时段比较与PCI组大致相同。结论　超声心动图     

Acute myocardial infarction. Treatment in the coronary care unit

Management of the patient with acute myocardial infarction is in flux. In the current "reperfusion era," many patients receive intravenous thrombolytic therapy and aspirin before admission to the coronary care unit. Appropriate use of drugs limits expansion of the infarct and reduces mortality rates in patients with uncomplicated myocardial infarction. Percutaneous transluminal coronary angioplasty may be necessary in those who are not candidates for drug treatment or who show recurrent ischemia after thrombolysis, while cardiac transplantation may be the only hope for patients with multivessel disease who are in cardiogenic shock. The "cocktail era," in which polypharmacy is both acceptable and effective, will likely be the next stage in management of acute myocardial infarction.     

New Accelerated rt-PA Strategy Has Sufficient Advantage over Older Streptokinase Strategies that It should Be the Trhombolytic Strategy of Choice in Anterior and Large Infarctions

The major goal of myocardial reperfusion therapy is to restore normal coronary blood flow as quickly as possible and to maintain coronary patency in the highest number of patients with acute myocardial infarction. Recent studies support the hypothesis that more rapid and complete restoration of coronary flow through the infarct-related artery results in improved ventricular performance and lower mortality. Accelerated tissue plasminogen activator therapy appears to produce the most favorable effects compared to other lytic strategies, particularly in patients with anterior and large myocardial infarctions. However, the finding in GUSTO II trial, that even with the best strategy only 54% of patients had TIMI grade 3 flow, suggests that further improvement in the treatment of acute myocardial infarction may be possible in the future. The effectiveness of thrombolytic therapy may be enhanced by earlier identification of evolving myocardial infarction and reduced time delays in the initiation of thrombolytic therapy, bolus thrombolytic therapy, new thrombolytic agents, or more potent adjunctive antithrombotic strategies.     

Acute MI: role of thrombolysis and intervention

Several issues confront the physician treating the patient with an acute infarction. If the patient is a thrombolytic candidate, a 20 to 30 per cent failure rate still exists, and it is difficult to predict on clinical grounds who has had a successful trial of thrombolytics or not; therefore, considerable clinical judgment must be applied. If the patient has relief of pain and diminished ST segment elevation, it is likely that thrombolytic therapy has been successful. Limitations concerning the benefits of thrombolytic or angioplasty therapy for the acute infarction also exist with regard to baseline patient characteristics. Older patients, especially women, seem to have more complications and less beneficial results from acute revascularization than do others. Patients with anterior infarctions as compared with posterior or inferior wall infarctions probably have a higher benefit from intracoronary thrombolysis. The acute myocardial infarction patient can be treated in multiple ways. Based on the preceding information and our own clinical experience, some recommendations can be made. Other sources with their own recommendations are available as well. First, because of the uncertainty still present in deciding optimum therapy for any given patient, as many patients as possible should be included in randomized prospective clinical trials that are now ongoing. If the patient or treating physician elects not to take part in such a trial, much of the therapy will be based on available resources. In small hospitals without acute catheterization or angioplasty facilities, intravenous thrombolytic therapy should be instituted as quickly as possible. In patients who are not able to receive thrombolytic therapy, acute catheterization with consideration for either angioplasty or acute bypass surgery should be undertaken if the patients are relatively young and early on in their course. Treatment of older patients, especially women, should be tempered by the knowledge that there are diminishing returns in aggressive approaches to these patients. It would appear that the presence of cardiogenic shock itself, although a predictor of higher cardiac mortality, should not preclude an aggressive approach and indeed this patient may benefit greatly from revascularization as well as pharmacologic and mechanical support of the cardiovascular system. If thrombolytic therapy without catheterization is undertaken, there remains the potential for either nonrevascularization or early closure.(ABSTRACT TRUNCATED AT 400 WORDS)     

Tissue plasminogen activator administration and nursing considerations

Intravenous thrombolytic therapy is rapidly gaining acceptance in the care of acute myocardial infarction (AMI) patients. There are several thrombolytic agents in use; however, this article will focus on tissue type plasminogen activator (t-PA). A thorough understanding of the benefits and risks associated with thrombolytic administration will be critical in the successful utilization of this form of therapy. Recent data show that infarct size is linked to mortality. In the 1980s, therapy for acute myocardial infarction patients is directed at salvaging myocardium and limiting infarct size. Prior to this, therapy consisted mainly of supportive care that resulted only in minor effects on the patients prognosis. Intracoronary thrombus has recently been recognized as the cause in most cases of acute myocardial infarction. Thrombolytic therapy represents a method of dissolving a thrombus and reestablishing blood flow to the previously occluded coronary artery. Early reperfusion of ischemic myocardial tissue can limit the amount of damage caused by evolving myocardial infarction. Intervention with thrombolytic therapy in the early hours of acute myocardial infarctions has been associated with reduction in the infarct size, improvement in left ventricular function and reduction in mortality. Nursing plays a critical role in ensuring the successful use of thrombolytic therapy by early identification of appropriate patients and accurate administration of the thrombolytic agent.     

Thrombolytics in infectious endocarditis associated myocardial infarction

The use of thrombolytics in the management of acute myocardial infarction in eligible patients is the accepted standard of practice. We present the case of an embolic myocardial infarction in the setting of acute infectious endocarditis, treated with thrombolytics, resulting in a massive intracerebral hemorrhage and the patient’s death. Historical and current literature has shown a consistent and significant incidence of concurrent intracerebral mycotic aneurysms in the setting of infectious endocarditis. Despite this, a literature review of contraindications to the use of thrombolytics rarely recognizes endocarditis as a contraindication. It is imperative that the etiology for myocardial infarction be identified; if contraindications to thrombolytic treatment exist, alternative therapeutic interventions must be pursued. This case highlights the importance of the correct etiologic diagnosis of myocardial ischemia, and increases the awareness of the significant risks of intracerebral hemorrhage associated with the use of thrombolytics in the setting of endocarditis.